Underwater telecommunication facility improvements over the years have brought geographically separated peoples closer together in a communication sense as well as enabling more extensive delving into the wonders of the undersea world. Such facilities usually include an electrical or lightwave signal communication cable having high pressure equipment enclosures interspersed along the length thereof. Improvements in facility hardware have largely focused upon the sophistication of equipment inside high pressure enclosures and, upon the interconnecting lengths of the cable. Enclosure technology has experienced relatively less technological improvement in the sense that robust rigid enclosures long have been employed and proportioned to enable them to withstand the rigors of pressure and corrosion at great depths in a body of water. A flavor of that technology is evident in the rigid enclosure for submarine cable system repeater components presented in U.S Pat. No. 4,172,212 to H. E. Heinzer. Such enclosures are often weighed in hundreds of pounds. During a cable system installation process, enclosures and cable are lowered into the ocean; and tensions in the cable exceed many thousands of pounds. Accordingly, the cable sections are designed to support such tensions, and the cable sections and enclosures must be designed also to withstand the enormous pressures experienced on the ocean floor.
Unfortunately, these ponderous enclosure structures also present a large discontinuity in the cable being installed due to their relatively larger diameter. Consequently, during deployment through sheaves on a cable ship, great local stress is imposed upon the cable at the points where it interfaces with enclosures and necessitates the imposition of limitations on cable design and upon the enclosure range of diameter/length ratios in order to avoid system failure. One attempt to mitigate the foregoing problem with rigid enclosures is represented by the articulated housing for a take-out connector as shown in U.S. Pat. No. 3,350,678 to K. W. McLoad. The rigid housing is also a problem in the application of braking forces to a cable as it is deployed from a cable ship because special provisions must be made to accommodate that diametric discontinuity when a portion of the cable including a housing must otherwise pass through the cable engine. More detailed background information relating to the cable and housing handling aspect can be found in a U.S. Pat. No. 3,310,213 to R. W. Gretter, and in several papers in The Bell System Technical Journal, Vol. 43, No. 4, Part 1 (July 1964). Those papers include "A Cable Laying Facility" by R. D. Ehrbar, pages 1367-1372 (indicating an unsatisfied interest in availability of a flexible housing); "Cable and Repeater Handling System" by O. D. Grismore, pages 1373-1394; and "Cable Payout System" by R. W. Gretter, pages 1395-1434.
Another aspect of the foregoing rigid enclosure problem is that involving the mentioned diameter/length ratio. Of course, the larger a rigid enclosure is in diameter and/or length, the greater will be the stresses imposed upon both the cable and the enclosure in the reeling upon and deploying from a drum or in passage through a sheave. Also, a rigid enclosure of a given diameter has a certain maximum possible length that can be sustained before the enclosure can no longer maintain its shape in a cantilever situation such as that encountered when a rigid housing passes through, e.g., a bow sheave of a cable ship. In addition, however, there are conflicting influences on enclosure design represented by, on the one hand, persistent advances in electronic and optical technology that have reduced the physical size of equipment that usually need be enclosed in a cable system enclosure and, on the other hand, increasing sophistication of functions to be performed that require additional space. The latter influence seems to be dominant at present, but it encounters the mentioned limitations on enclosure length and diameter.
Corrugated tubing has been used for various purposes in some fields, and in those uses benefit is generally taken of the flexibility of the corrugated structure in maintaining an essentially cylindrical passageway around some form of a curved path. Strength limitations of the corrugated device are usually a function of the material and its uncorrugated thickness. A corrugated aluminum enclosure is disclosed in "Mechanical Design and Test of 1200 KV Semi-Flexible SF.sub.6 Insulated Transmission Line" by P. C. Bolin et al. in IEEE Transactions on Power Apparatus and Systems, Vol. PAS-101, No. 6, June 1982, pages 1630-1637. Both helical and annular, or planar, corrugations are considered. A U.S. Pat. No. 1,826,666 to A. R. Lawrence shows a pipeline expansion joint employing a corrugated tubular conduit that is provided with external reinforcing rings having inside configurations that mate with the outside configurations of the corrugations to prevent total longitudinal collapse of the corrugations. Metal of sufficient thickness is employed in the corrugated conduit to withstand the internal pressure in the pipeline.
A method for forming elastomeric material into a convoluted (corrugated) tubing with a tight pitch and for an unspecified application is taught in a U.S. Pat. No. 3,714,311 to J. A. Stefanka. Several other corrugation forming methods are shown in U.S. Pat. No. 1,554,739 to J. E. Lewis, U.S. Pat. Nos. 3,407,102 to S. C. W. Wilkinson, and 4,342,612 to J. M. Lalikos et al.
A corrugated tube is included in a collapsible steering column assembly in a U.S. Pat. No. 3,401,576 to R. E. Eckels to absorb the energy of a driver's body during an accident while leaving intact the rotational coupling function of other parts of the assembly. Alternate convolutions are formed with different diameters in a boot for a manipulator arm to reduce the minimum collapsed length of the boot in U.S. Pat. No. 3,572,393 to G. A. Eisert. Ends of an uncollapsed corrugated tube are restrained in a vibration absorbing connector of U.S. Pat. No. 4,204,707 to T. N. Lincicome et al.,